<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>浮动练习</title>
    <style>
        .one {
            border: 1px solid black;
            /* overflow: hidden; */ 
        }
        .mo {
            width: 300px;
            height: 120px;
            background-color: purple;
            float: left;
        }
        .x {
            height: 300px;
            background-color: orange;
        }
        .clearfix:before, .clearfix:after {
            content: "";
            display: table;
        }
        .clearfix:after {
            clear: both;
        }
        .clearfix {
            *zoom: 1;
        }
    </style>
</head>

<body>
    <div class="one clearfix">
        <ul>
            <li class="mo">1</li>
            <li class="mo">2</li>
            <li class="mo">3</li>
        </ul>
        <!-- <div style="clear: both;"></div> -->
    </div>
    <div class="x"></div>
</body>

</html>